If you build a ship that served under two different nations during the WW1 - WW2 timeframe, can you switch back between them? A specific example would be SMS Goeben (Moltke class), which was sold to the Ottoman Empire, and later served in the Turkish navy. This would mean it could be axis (as a German or Ottoman ship) or allies (Turkey did officially declare war on Nazi Germany at the end of WW2.)
Yes. I cannot think of any clubs that don't. A few more examples: DKM Prinz Eugen, given to USA as a war prize and sunk in nuclear testing, and SMS Prinz Eugen, an Austro-Hungarian battleship that was given to France as a war prize. BTW, technically Japanese ships can be Allied, since Japan did side with the Triple Entente during WWI. How many other nations are flip-floppers?
Using DKM Prinz Eugen as an allied ship IS frowned upon, and some clubs will not allow WW2 IJN ships to be used as allies based on WWI alliances. Check with people from the club you will be battling with to be sure what is acceptable and what isn't.
For Italy and Japan, I would go with "as built" can be used either way, but refitted have to be Axis. My opinion only, your milage may vary.
The other example that I can think of besides Moltke would be the Admiral Hipper class cruiser - one of them was sold to the Soviets before they entered the war but was never completed.
Lutzow wasn't it. I have seen a picture of it in Soviet service. He was used as a floating battery in Leningrad I think.
There was one French escort that the Itialians raised from the bottom of Toulon harbour and got running again. (Out of 42 major ships the German Army tried to capture). The German army asked the German Navy how hard it would be to capture ships sitting in a port. The German navy ( with experience only 20 years earlier) said it wouldn't happen. The German Army ignored them - only to find out they were right. That doesn't mean that the French can't shoot at anyone! They did shoot at almost everyone! Their capital ships were never on the Axis side. Ask the HMS Barham how a 15" shell in the bow feels... (The Richelieu at Dakar for history buffs)
A better question might be what did the French show their adversaries more of--shells or white flags?
We allow an UN-refitted Japanese WW1 ship to be used as an Allied ship. Once the WW2 configuration is adopted, it is Axis J